Given text and a desired line length, wrap the text as a typewriter would...

typewriter.py

# Given text and a desired line length, wrap the text as a typewriter would.
# An exercise from MITx: 6.00.1x Introduction to Computer Science and Programming Using Python.

def typewriter(text, lineLength):
  """
  Given text and a desired line length, wrap the text as a typewriter would.
  Insert a newline character ("\n") after each word that reaches or exceeds
  the desired line length.

  text: a string containing the text to wrap.
  line_length: the number of characters to include on a line before wrapping
    the next word.
  returns: a string, with newline characters inserted appropriately. 
  """
  def insertNewlinesRecur(wordList, remainingLineLength):
    if not wordList or len(wordList) == 0:
      return ""
    else:
      word = wordList[0]
      if len(wordList) > 1:
        wordList = wordList[1:]
      else:
        wordList = None
      if len(word) > remainingLineLength:
        return word + "\n" + insertNewlinesRecur(wordList, lineLength)
      else:
        remainingLineLength -= len(word) + 1
        return word + " " + insertNewlinesRecur(wordList, remainingLineLength)
  if not text:
    return None
  else:
    return insertNewlinesRecur(text.split(), lineLength)